1. Field of the Invention
The present invention relates to fuel vapor adsorbing devices for adsorbing residual fuel vapors that remain in an intake conduit of an induction system of an internal combustion engine during the stopping of the internal combustion engine.
2. Description of the Related Art
For example, Japanese Laid-open Patent Publication Number 2001-227421 teaches a fuel vapor adsorbing device for preventing outside leakage of residual fuel vapors that remain in an intake conduit of an induction system when an internal combustion engine is stopped. In this device, adsorbing materials are disposed in the intake conduit for adsorbing the fuel vapors.
As shown in FIG. 11, in a known device, the adsorbing materials 90 are entirely and evenly attached to an inner wall surface of a surge tank 94 that constitutes the intake conduit 92 of the induction system.
However, in the known device in which the adsorbing materials 90 are attached or adhered to the inner wall surface of the surge tank 94, only certain areas (i.e., non-adhering areas) of the outer surfaces of the adsorbing materials 90 are exposed. Therefore, the adsorbing materials 90 can only adsorb the fuel vapors in the exposed areas of the outer surfaces thereof. In other words, the adsorbing materials 90 cannot adsorb the fuel vapors in the remaining areas or non-exposed areas (i.e., adhering areas) of the outer surfaces thereof. As a result, the adsorbing materials 90 have limited effective adsorbing areas. Conversely, during operation of the internal combustion engine, the fuel vapors adsorbed to the adsorbing materials 90 will be purged or released therefrom by means of intake air. However, such adsorbed fuel vapors can also only be released from the exposed areas of the adsorbing material outer surfaces. That is, the adsorbed fuel vapors cannot be released from the non-exposed areas of the adsorbing material outer surfaces. As a result, the adsorbing materials 90 have limited effective releasing areas. Thus, the adsorbing materials 90 have a poor availability or utilization.